A) Field of the Invention
The present invention relates to a probe unit and its manufacture, the probe unit being used for conduction tests of electrodes, terminals and the like of an electronic device (test body) such as a semiconductor integrated circuit and a liquid crystal display panel.
B) Description of the Related Art
A conduction test is generally performed for products such as semiconductor integrated circuits, liquid crystal display panels and printed circuit boards in order to check whether these products can operate satisfactorily meeting the requirements of specifications.
During this conduction test, probe pins formed at or near at the tip of a probe unit are abutted upon juxtaposed electrodes of a semiconductor integrated circuit, a liquid crystal display panel, a printed circuit board or the like. Probe units to be used for conduction tests include an “independent wiring” type and a “plunger” type. Probe pins of a probe unit of the “independent wiring” type are made in contact with electrodes of a test body in one-to-one correspondence to establish independent conduction for each electrode. Probe pins of a probe unit of the “plunger” type are intended to be in contact with a plurality of electrodes of a test body at the same time.
Electrode layers are juxtaposed nowadays at a microfine pitch along the edge of a glass plate constituting a liquid crystal display panel. In order to perform a conduction test for such a liquid crystal display panel, the conduction test apparatus is required to have a probe unit whose probe pins are compatible with the microfine pitch of the electrode layers.
The pitch of electrode layers is 0.1 mm or smaller. It is difficult to form a probe unit compatible with such a pitch through mechanical punching.
Probe units are therefore manufactured by etching or plating.
A method of manufacturing a probe unit of the independent wiring type is disclosed, for example, in the Japanese Patent Publication No. 2552084.
This Publication proposes to adhere a number of leads whose workpiece is coupled by tie bars and cut the tie bars after adhesion.
A method of manufacturing a probe unit of the independent wiring type is disclosed also in JP-B-7-56493. This Publication proposes to etch conductive contact terminals into a predetermined shape and layout, adhere the conductive contact terminals to an insulating member, and thereafter cut both ends of the conductive contact terminals.
Another method of manufacturing a probe unit of the independent wiring type is disclosed in JP-A-11-337575. This Publication proposes to coat resist on a plated metal layer to a desired thickness, set a mask having a predetermined pattern to the resist surface, perform exposure and development processes to remove unnecessary resist, deposit thin plated copper seed layers on the exposed plated metal layer, grow probe pins having a desired thickness on the seed layer, and dissolve only the copper seed layer to separate the probe pins. This Publication further proposes to form holes through a substrate with a drill or a laser and fit positioning projections formed on the probe pins into the holes to fix the probe pins to the substrate.
Probe units of the “plunger” type are proposed in JP-A-8-110362 and JP-A-11-64425.
Narrow pitches of electrodes of a test body and probe pins make it difficult to realize position alignment between the electrodes and probe pins. JP-A-10-339740 discloses a method of positioning and fixing a probe unit (contact probe) having probe pins formed on a substrate (film) to a probe device.
With the method described in Japanese Patent Publication No. 2552084, however, it is very difficult to adhere leads to an insulating base at a high precision of position alignment. In addition, when tie bars are cut, leads may be damaged.
With the method described in JP-B-7-56493, it is very difficult to adhere conductive contact terminals to the insulating member at a high precision of position alignment.
With the method described in JP-A-11-337575, the thin plated copper seed layer has a small contact area with solvent so that it is hard to dissolve the seed layer and it takes a long time to separate the probe pins. It is also difficult to form holes through a substrate with a drill or a laser at a high precision and to dispose the probe pins at positions corresponding to the holes.
With the method disclosed in JP-A-10-339740, positioning holes for positioning and fixing a probe unit to a probe device are formed through a substrate by a process different from the lithography process of forming probe pins. It is therefore difficult to realize a high position alignment precision between probe pins and positioning holes. It is therefore difficult to obtain sufficiently high position precision between the probe device and probe pins and between electrodes of a test body held by the probe device and probe pins.